Calculus 2 Geometric

Question

Consider the sequence an = 12,16,20,24...,4n+4 

How many terms are there in the sequence? Your answer will be in terms of n. 

What is the second-to-last-term (in terms of n)?

sum of all the terms in the sequence, in terms of n

Answer 1

This is an arithmetic sequence defined for any value of n...that is there is a countably infinite number of terms.

There is NO last term and consequently no "2nd to last" term.

In order to specify a sum you must specify the terms which you wish to sum...you certainly cannot sum an infinite number of terms of this sequence.